The reciprocating plunger pump as a volumetric pump, it reaches the purpose of delivering liquid by the periodical change of the volume in the working chamber. The mechanical energy is converted directly into pressure energy for delivering the liquid when it works.
As mentioned above, a reciprocating plunger pump can reach the purpose of outputting the liquid under a certain pressure by pulsed press to the liquid by means of periodical reciprocating motion of the plunger (also known as a piston); the reciprocating motion is obtained by motion transformation mechanism from transformation of rotation motion. In a traditional reciprocating plunger pump, the motion transformation mechanism adopts the crank connecting rod mechanism, which makes the reciprocating plunger pump huge and cumbersome due to the existence of the connecting rod which requires reciprocating swing while it works in the crank connecting rod mechanism.
To overcome the defects of the traditional crank connecting rod mechanism mentioned above, Chinese patent application CN85100358B published a Slider Crank Reciprocating Piston Internal Combustion Engine; Chinese patent application CN85100359B published a Slider Crank Reciprocating Piston Compressor; Chinese patent application CN1067741C published a Double Slider Crank Reciprocating Piston Internal Combustion Engine; Chinese patent application CN1067742C published a Multi-Slider Crank Reciprocating Piston Internal Combustion Engine. In the transformation mechanism of reciprocating motion and rotation motion in the internal combustion engines and compressors mentioned in the above Chinese patent applications, the crank connected rod mechanism is replaced by the slider crank mechanism, which comprises a slide block, a piston and a crankshaft, wherein the slide block is provided with an eccentric circular hole, the piston seat is provided with an accommodation bore for the slide block. When an operator assembles, the slide block can be located into said accommodation bore of the slide block which the slide block can be rotated in said accommodation bore of the slide block; the crankpin of the crankshaft can be located into said eccentric circular bore which the crankpin can be rotated in it.
Taking the work of internal combustion engines for examples, the motion transformation progress of the slider crank mechanism is shown as follows: the piston is pushed to move by the expansion due to burning the combustion gas inside the chamber, which will cause the reciprocating motion of the slide block provided in it to move by the movement of the piston, meanwhile the slide block is also in rotation motion in said piston, the compound of said reciprocating motion and rotation motion leads the central axis of the eccentric circular bore which is located on the slide block to be in rotation motion by the central axis of the crankshaft; said central axis of the eccentric circular bore is overlapped with the axis of the crankshaft's crankpin, which can reach the purpose of the transformation from the reciprocating motion of the piston to the rotation motion of the crankshaft. The compressor can adopt the same mechanism, the crankshaft is drove in rotation by the electrical machine, which achieves the reciprocating motion of the piston by the coordination between the slide block, the crankshaft and the piston and then to work on the compressed medium.
The slider crank mechanism which is published in the above-mentioned Chinese patent applications can be applied into the traditional reciprocating plunger pump to replace the crank-connected rod mechanism. However, because the reciprocating plunger pump has the characteristics which are different from said internal combustion or the compressor, it has to be improved according to the characteristics of the reciprocating plunger pump itself during the application of the slider crank mechanism into the reciprocating plunger pump.